Can't get ESCs to calibrate - Pixhawk fails pre-arm checks

#1

Hi all,

I looked through the questions already answered, and I can’t find a solution. I have the drone built and have successfully bound the receiver and transmitter. I even updated the Pixhawk firmware successfully with Mission Planner.

My problem is that I unable to calibrate the ESCs and get the motors to respond. I have removed the UBEC lines in three of the motors as instructed in the video. When I plug in the LIPO battery I hear the beeps from the ESCs, and the lights on the Pixhawk come on; however, the big LED right behind the arrow flashes through a lot of colors and then just keeps flashing yellow twice. According to the Ardupilot website, that means ‘Failing pre-arm checks (system refuses to arm)’. Any suggestions on what I might being doing wrong?

#2

It sounds like the ESCs are calibrated and the pre-arm check is failing because there isn’t a GPS lock. What do you see on the Mission Planner HUD? This is a normal issue when doing this indoors. Moving near a window and away from building obstructions might help. Also look at the MP Messages tab.

#3

I took the drone outside well away from buildings and I still get the two flashing yellow lights. Mission Planner tells me “PreArm: 3D Accel calibration needed”. The transmitter is binded with the drone but no matter what, the motors do not respond to the throttle. The transmitter appears to be working fine when I move the gimbels around according to Mission Planner. I will go ahead and complete the 3d Accel calibration, but any suggestions on why no movement from the motors?

#4

The motors won’t engage until you have completed the pre-arm check and pressed the safety switch off. Sounds like you are on the right track by re-calibrating the vehicle. Also, often magnetic anomalies at home might warrant re-calibration of the compass each time you are flying in the field.

#5

Making progress… Completed the 3D Acceleration calibration. Now when I turn on the power up the drone and the R/C controller, and press the safety switch, the Pixhawk main LED turns as flashing blue for few seconds, then it begins flashing green. However, the motors still do not spin up when I increase throttle on the controller.

#6

When it starts flashing green that means you have GPS lock and you then just need to arm the throttle.

Move the left stick to the lower right-hand corner and the motors will engage.

Use all safety precautions and ready to fly.

#7

That worked; however, only two motors (right front, and back left) come on. The motors on the left front and back right do not work.

#8

OK try one more esc calibration. Use the one with Mission Planner. If that doesn’t work then will next need to look at your wiring.

Consider using the MP Motor Test.

#9

That did it. All four motors are now functioning. Only thing I noticed is that even when the throttle is in the lowest position the motors are spinning at a low speed. Is this normal?

#10

Yes it’s normal. Congratulations!

#11

Thank you for all your help and assistance.

#12

I’m having the same issues you had (unable to calibrate ESC, Pixhawk flashing yellow).

How did you manage to calibrate the 3D accelerometers? I cannot see that step in the tutorials (https://dojofordrones.com/courses/how-to-build-a-raspberry-pi-drone/).

thanks!

#13

Start here and then go to each next page. I recommend using the MP esc calibration rather than moving the stick as shown.

https://ardupilot.org/copter/docs/common-accelerometer-calibration.html

Let me know how it goes.

#14

Thanks @jax200 - that’s super helpful. I’ve managed to calibrate the GPS and compass now. The ESCs are still not calibrating, and after a single run of not having the yellow flashing light on the Pixhawk, it’s back to flashing yellow each time again - but it still feels like it is a small step in the right direction, so thank you!

Re getting the ESC to calibrate, it feels like it may be linked with a myriad of other oddities my drone is displaying (at least compared to what I’m seeing in the video tutorials), so I’ll create a new thread in case they all related.

101 odd behaviours - maybe interrelated
closed #15

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